The present invention relates to a magnetoresistive element utilizing the magnetoresistance effect, and particularly to a magneto-resistive element that can be well adapted to a sensor for detecting a magnetic field and to a magnetic head.
In a conventional magnetoresistive element utilizing an Ni-Fe alloy (a so-called permalloy) film having high permeability, the magnetic characteristics are subject to change depending upon the materials constituting the element and stress exerted in using the element. In order to prevent the magnetic characteristics from changing, therefore, a permalloy film having a composition of zero magnetostriction has heretofore been used. However, the composition range in which the magnetostriction of the permalloy film remains zero is very narrow. With a thin film formed by evaporation or sputtering, in particular, it is difficult to precisely control composition. Moreover, the magnetostriction of permalloy film varies greatly depending upon the kind and amount of impurity elements contained in the film. Accordingly, electromagnetic properties of the element change depending upon stress.
The following references are cited to show the state of the art: (i) A. V. Pohm, C. S. Comstock and L. Perrey; IEEE Trans. Mag., MAG-20, No. 5, 863 (1984), and (ii) J. A. C. van Ooyen, M. F. Druyvesteyn and L. Postma; J. Appl. Phys., 53(3), 2596 (1982).